Abstract
Visual memory enables a viewer to hold in mind details of objects, textures, faces, and scenes. After initial exposure to an image, however, memory rapidly degrades. To gain insight into this process, and to better understand memory maintenance, we examined whether degradation depends on the amount of information being maintained. We collected high-quality forgetting functions, testing a five-hundredfold range of durations (0.03–16 s) and a twelvefold range of loads (1–12 objects) in a working memory task for object color. We found that the rate of forgetting depends on the total amount of information held in mind, with lone memories lasting longest (estimated mean lifetime of 157 s) and higher loads leading to progressively shorter lifetimes (correlation between load and lifetime, r = 0.98). Load-dependent forgetting implies that simultaneously-held memories interact during maintenance, perhaps because they compete for a shared commodity such as "slots", "resources", or time. In some cases, the lines of the forgetting functions for each load cross. At short durations, presenting a greater number of objects causes more to be remembered (e.g., at 2 s, more objects are remembered at load 8 than at 2). At long durations, however, the opposite is often true — presenting a greater number of objects causes fewer to be remembered (e.g., at 16 s, fewer are remembered at load 8 than at 2). The presence of crossovers suggests flawed strategy choice or execution by the participants, who presumably control how much to encode and maintain. Like a bodybuilder who herniates a disk by straining to lift too heavy a weight, our participants performed worse by encoding or maintaining too much — they overreached. Together, these results suggest that the process of active maintenance is dynamic and depends on how much information is being held in mind.
Meeting abstract presented at VSS 2014